Ballpoint-pen tips and method of making same



A. G. ROSA March 29, 1966 BALLPOINT-PEN TIPS AND METHOD OF MAKING SAME Filed July 9, 1962 AGENT.

United States Patent 3,242,906 BALLPOINT-PEN TIPS AND METHOD OF MAKING SAME Anthony G. Rosa, 155 Park Ave, Lyndhurst, NJ. Filed July 9, 1962, Ser. No. 208,211

1 Claim. (Cl. 12042.4)

My present invention relates to a ballpoint pen and, more particularly, to an improved pen tip and method of making same.

It has been known, heretofore, to provide a socket adapted to receive a ball forming therewith a ballpointpen tip, with axially extending channels opening at the surface of the ball and communicating with the ink-supply bore for increasing the amount of ink fed to the ball. Generally, the socket was formed with an annular seat for the ball in substantially line contact therewith. High axial pressure was then applied to the ball in order to deform the seat and shape it to conform to a spherical sector hugging the ball. Heretofore, the socket was pro vided with the channels, and the balls then seated in the -recess under the aforementioned pressure so that the channelswere often pinched shut and could only permit the passage of limited quantities of ink, thus defeating the. purpose of the channels.

It is an object of my invention, therefore, to provide a method of making ballpoint-pen tips whereby a continuous and plentiful supply of ink to the writing surface of the ball is insured.

It is another object of this invention to provide a pen point of the character described which is less susceptible to wear than hitherto known tips while affording a uniform and plentiful supply of ink to the writing ball.

These objects have been realized, according to the invention, by a method of forming the tip of the ballpen which comprises the steps of forming a recess in a body adapted to receive a ball, providing the recess with a seating surface constituting a spherical sector conforming substantially to the surface of the ball and providing axially extending channels in the body terminating at the seating surface while opening into the ink-supply bore which has previously been provided therein; the ball may then be seated in the recess. The body is provided with a wall portion of the recess extending beyond the seating surface and adapted to be clenched or clamped around the ball forwardly of a diametral plane thereof perpendicular to the axis of the body in order to secure the ball in engagement with the seat. The ball is forced into contact with the seat under pressure but cannot deform the walls of the channels in such manner as to constrict the latter since the spherical seating surface engages the ball over a substantial region of its periphery, and there is little tendency for the material constituting the body to deform so as to block the channels. Moreover, the pressure is applied axially to the ball and the seating surface which is so shaped as to transmit substantially all of the force applied to it in radial direction, there being no component of the applied force effective angularly about the axis of the body which might otherwise 1 cause a deformation of the latter so as to constrict the channels.

According to another feature of my invention, the body is provided with an auxiliary supporting member of har ened or wear-resistant material, in preferably, point contact with the ball along its periphery within the annular seating surface. The auxiliary supporting member may be an insert (e.g., of hardened steel or bearing stone) which is held in place within the recess by the radially extending ribs defining the aforementioned channels. Generally, the body will be formed from a relatively soft material, such as brass, Phosphor bronze or stainless steel, in contrast with the hardened member which may be a ruby, sapphire or the like. The wear-resistant member may be provided with a convex surface osculating the ball and, consequently, may be of generally spherical or hemispherical configuration.

It is also possible to employ a block or the like with a substantially fiat bearing surface extending transversally to the axis of the body and tangent to the ball, thus also contacting the latter at substantially a single point.

The above and other objects, features and advantages of my present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIGS. 15 are axial cross-sectional views through a ballpoint-pen tip showing successive'steps in its manufacture;

FIG. 6 is a plan view of the body prior to the seating of the ball therein;

FIG. 7 is an axial cross-sectional view of a tip pro vided with an insert;

FIG. 8 is an end view of the tip of FIG. 7;

FIG. 9 is a view similar to that of FIG. 7 showing another embodiment of the invention;

FIG. 10 is a plan View of a tool employed in the formation of the ball seat;

FIG. 11 is a plan view of a tool for forming the channels therein; and

FIG. 12 is an end view of the latter tool.

In FIG. 1 of the drawing I show a ballpoint-pen tip body 10 having a frustoconical forward portion 11 which, according to the invention, is axially drilled to form a recess 12 at its forward end. The mouth 13 of recess 12 is adapted to receive a ball, as will be described in greater detail hereinafter. After the initial drilling of the body 10 to form the recess 12, a further bore 14 is provided. This bore, which extends axially along the body and opens into the sleeve or tube (not shown) forming the ink reservoir, is coaxial with the recess and terminates at the conically sloping floor 15 thereof. This beveled floor (FIG. 2), in earlier ballpoint-pen constructions, served as a seat for the ball which was thrust axially thereagainst in order to shape it to conform its configuration to that of the ball pen; thus, any longitudinal channels terminating at the bevel surface 15 were constricted owing to the plastic deformation of the ma terial along the walls of such channels upon the compression which seated the ball.

As indicated in FIG. 3, the present invention avoids this disadvantage in that it provides for the shaping of a seat 1a which conforms to a spherical sector whose radius is identical with that of the ball to be lodged in recess 12. The spherical sectoral seat 16 is, advantageously, formed by turning (e.g. with the aid of a boring tool such as that shown in FIG. 10) so that it may be provided either subsequently to the formation of channels, or prior thereto. In FIG. 4 I show the channels 18 which are angularly spaced about the axis of the body it and extend longitudinally to form radial ribs 19. A flutin g tool such as that shown in FIGS. 11 and 12 may be employed to form the channels, the tool being forced axially by means of a suitable press through the mouth 13 of the body. The use of a fluting tool eliminates the possibility that burrs may be formed along the edges of the ribs .to constrict the channels 18 which supply ink to the ball over a substantial portion of its surface although it locks bore 14. The terminal walls 16' of the channels 18 are, like the seat 16, of spherical sectoral configuration and diverge upwardly to provide a smooth flow of ink to the ball.

In FIG. 5 I show the ball 20, which is received in the recess 12, held against the complementarily shaped seat 16. A portion 21 of the body 10, having a relatively small Wall thickness, extends forwardly beyond a diametrical plane 22 of the ball transverse to the axis of body and is clenched around the ball to hold it in place. The clenching operation is well known and may be accomplished with the aid of radial pressure, eg. via forming dies. In general, the axially extending bore 14 may have a diameter of about /2 mm. While the channels have a radial depth of approximately 4 mm. and a total length equal approximately to the radius of the ball; the diameter of the ball is about 1 mm. From FIG. 6 it may be seen that five channels 13, which are angularly equispaced (eg by 72) about the axis of the body, are provided. The total cross-sectional area of these channels, regardless of the number provided, should be at least equal to that of bore 14.

In FIG. 7 I show a body 30 which is provided with channels 38 terminating at a spherical seat 36 for a ball 31 as previously described. The ribs 39 between the channels 38 are, however, formed with shoulders 35, against which rests a wear-resistant insert 49 substantially in point contact with the ball. The insert thus lies along the axis of the body 39 and is surrounded by the spherical seat 36..

While the wear-resistant insert 40 is shown to be a sphere in FIG. 7, it should be noted that any convex body bers may also be employed. In FIG. 9 I show a block 41' whose planar surface 42 is tangent to the ball 31' and extends transversely to the longitudinal axis of the body 39'. The wear-resistant member 41 is held against axial displacement: by the shoulders 35' of ribs 39 which de fine between them the channels 38. The wear-resistant inserts or members 46, 41 may be gem stones of ruby, sapphire or like material whose hardness is greater than that of the stainless steel ball, or of steel or another metal having a hardness at least equal to that of the ball. The body 10, 36, 30 which forms the spherical seating surface 16, 36, 36' may be of relatively soft material'such as brass, Phosphor bronze or the like. It is also possible for the body to be composed of a material having the same hardness as that of the ball (eg. of stainless steel).

In FIG. 10 I show-a boring tool 50 which carries a cutter bit 51 whose cutting edge 52 is rounded to conform to an arc of the sphere or ball 20, 31, 31 to be received in the seat formed by the tool. The body may then be rotated at relatively high speed while the too] bit 51- is displaced axially into the recess 12 to cut the sphericalsectoral side 16, etc. The bit is, of course, provided with the required rakes and clearances.

The flutingtool 60 shown in FIGS. 11 and 12 is provided with ribs 61 which forms the channels 18, 38, 38' when the tool is thrustaxially into the recess 12. The end 62 of this tool is rounded generally spherically to form the terminal walls 16' etc. of the respective tip bodies.

I have also discovered that it is possible to control the width of the aforementioned axial channels by suitably varying the bevel (FIG. 2) in the event that the spherical seat 16 is not machined in the pen tip and the ball is-forced axially into the latter to form its seat. In

4 this connection, I have found that the material of the tip displaced by the ball flows substantially radially and does not obstruct the channels when the floor of the recess 12 includes an angle substantially less than with the axis of the tip. Thus, the beveled surfaces against which the ball is urged may, in an axial cross section such as that shown in FIG. 2, include an angle of the latter having been found to produce optimum results. The channels are then formed by means of a fluting tool substantially as described with reference to FIG. 11. After the channels have been formed, the ball (e.g., ball 20) is forced against, the beveled seat 15,

which converges at an angle of about 35 toward the axis of the tip, to form the spherical seat 16.

The invention as described and illustrated is believed to admit of many modifications and variationswithin the ability of persons skilled in the art, all such modifications being deemed included within the merit andscope of the appended claim.

Iclaim:

A ballpoint-pen tip comprising a body having an axis and provided with an axially extending ink-supply bore, said body being provided with a recess at one axial end of said body having a mouth opening outwardly, and with a concave annular seat conforming to a spherical sector surrounding said axis at a location remote from said mouth; a ball having a periphery conforming substantially to said spherical sector received in said recess in contact with said seat anda bearing member of wearresistant material of a hardness at least equal to that of said ball in axial engagement and in substantially point Contact with said ball and surrounded by said seat, said bearing member being of spherically convex configuration in the direction of said ball and oscillating said ball along said axis, said body being provided with a plurality of angularly spaced axially extending channels in a wall of said bore terminating at said seat, said channels being of substantially uniform cross-section throughout their axial length and surrounding said bearing member, the wall of said bore being provided with a shoulder axially spaced from said seat in a direction away from said mouth, said member being seated against said shoulder.

References tilted bythe Examiner UNITED STATES PATENTS 2,53 6,124 1/1951 'Bolvin et al -42.4 2,646,761 7/1963 Knobel 29-441 2,718,051 9/1955 Cloutier 29.441 2,911,949 11/1959 Beckwith 12042.4 2,983,253 5/ 1961 Henriksen 12042.4.

FOREIGN PATENTS 1,035,935 4/1953 France.- 1,078,547 5/1954 France.

411,016 5/1934 Great Britain.

613,408 11/ 1948 Great Britain.

717,668 11/1954 Great Britain.

0 EUGENE K. CAPOZIO, Primary Examiner.

GEORGE NINAS, 1a., Examiner. ELIAS I-IQRQWITZ, Assistant Examiner. 

